Conventionally, there is known an obstacle detecting apparatus including a plurality of sensors and a control device, which are connected to each other through a bus (for example, see Japanese Patent Laid-Open Publication No. 2003-152741). According to an obstacle detecting apparatus disclosed in this patent reference, for example, a control device sequentially sets, through a bus, the IDs of connecting positions of the ultrasonic sensor from the ultrasonic sensor closest to the control device based on pre-stored connection sequence and IDs of ultrasonic sensors. Then, when the ID setting is completed for the last ultrasonic sensor, the control device starts communicating with each of the ultrasonic sensors.
In the above-described conventional obstacle detecting apparatus, each of the ultrasonic sensors functions as a sensor only after a parameter such as an ID to be set can be normally received in the first communication with the control device. Therefore, unless the parameter can be normally received, each of the ultrasonic sensors cannot function as a sensor.
Accordingly, if a communication error occurs during parameter setting, a process of setting a parameter again or stopping the communication with a sensor, which cannot receive a parameter is required to be performed.
In the parameter resetting, however, it is required to retransmit a parameter after each of the sensors is once powered OFF. Therefore, a long time is needed to reset a parameter so as to reestablish the communication. Moreover, if the communication with the sensor that cannot receive the parameter is continuously interrupted in the case where a temporary communication error such as the interference of an electromagnetic wave noise occurs, the communication with the sensor cannot be reestablished thereafter.